1. Technical Field
This document relates to methods and materials for detecting nucleic acids. More specifically, this document relates to methods for detecting nucleic acids using two 5′ labeled oligonucleotides that contain sequences complementary to each other as well as sequences complementary to different portions of a target nucleic acid.
2. Background Information
The fluorescence resonance energy transfer (FRET) mechanism has been incorporated into a variety of assays for detecting nucleic acids, including molecular beacons and Taqman assays. See Epstein et al. (2002), Analytica Chimica Acta, 469:3-36. With molecular beacons, a single stranded probe is used that can form a hairpin structure. The probe is dual labeled, containing a fluorophore on one end and a quencher on the other end. When the probe is in the hairpin conformation, fluorescence is quenched. Upon hybridization to its target, fluorescence is observed. Taqman assays rely on the 5′-exonuclease activity of a DNA polymerase to digest a dual-labeled probe, which physically separates the fluorescent labeled nucleotide from the quencher and results in an increase in fluorescence. A need exists for a method of nucleic acid detection that does not require dual labeled probes or more than two oligonucleotides.